Three times so this thing will scroll on for the next few years. Other values
for tbl would work too; I just didn’t bother to do anything better. I’ve
written clearer code, but that wasn’t really the point either.

I actually screwed this up twice: first I didn’t remember to treat the 0
entries correctly (i.e. I should have skipped those days, whereas I ignored
them entirely); second, it seemed like I was getting hit by timezone issues
where everything was shifted up a block.

In retrospect, I should have first produced a mini-contributions graph
generator (i.e. one that takes a Git repository and produces what GitHub would
do), validate that against an existing user/repo, then use that to ensure it’d
work the first time. I did a similar thing to ensure I had the data correct,
by producing a graph directly from the data: